Effect of oxidation pretreatment by hydrogen peroxide on iron removal from wastewater of a sulfuric acid iron-pickling process

Abstract

In this paper, a new method for the treatment of wastewater from a sulfuric acid iron-pickling process is described. A two-stage treatment process that includes a hydrogen peroxide oxidation first step based on Fenton reactions, and a lime precipitation second step, was compared with the one-stage conventional treatment process that includes only lime precipitation. The objective of the study was to demonstrate the beneficial effect of oxidation as a pretreatment method because the conventional treatment method cannot meet the Greek Emission Limit Values for effluent disposal to surface waters at any pH, whereas the proposed method can. Complete removal of iron (<1 mg/L) and sulfates (<500 mg/L) can be achieved. In contrast, at the same pH using the conventional method, the concentrations of iron and sulfates in the effluent are greater than 500 and 2500 mg/L, respectively. Furthermore, COD and BOD are reduced by the proposed process (>90%) as a result of oxidation. © 2004 American Institute of Chemical Engineers Environ Prog,.